The present invention relates to a resist developing apparatus and more particularly, to a resist developing apparatus for developing a resist layer mounted on a work piece such as a semiconductor wafer, a mask for making a semiconductor device, a photodisk, etc.
Conventionally, a resist developing apparatus of the kind are typically of such design that chemical liquids for developing treatment are sprayed over a semiconductor wafer W housed in a developing tank D by means of a spray means N such as a nozzle, whereby a resist layer of the wafer W is developed, as described in Japanese Patent Laid-open Publication No. 166032/1982, for example, and as illustrated in FIG. 1.
Generally, the chemical liquids referred to above include, in addition to the so-called developer for dissolving the resist layer, a pretreatment liquid to be used prior to the spraying of the developer for removing variations of resist sensitivity due to change of the wafer with time, and a post-treatment liquid for washing the wafer after the developer spraying.
With a recent trend toward higher-density oriented resist patterns, the requirements for conditions of the developing process, especially for temperature conditions, have been increasingly becoming crucial. In an attempt to meet such requirements, an electric heater H.sub.1 is disposed in the developing tank D to provide heat so as to maintain the temperature of the tank at a specified level; and a temperature control unit T provided with an electric heater H.sub.2 is employed to preheat the developer, one of the different kinds of chemical liquids to be used in the developing process, to a specified temperature. In addition, as FIG. 1 shows, an electric heater H.sub.3 is coiled around a developer supply pipe L in order to prevent a drop in the temperature of the developer flowing in the pipeline L. Through such arrangement the temperature of the developer to be sprayed by the spray means N onto the wafer is intended to be maintained at the predetermined value.
However, the use of such heaters H.sub.1, H.sub.2, H.sub.3 as heat sources for regulating the temperature within the tank D and the temperature of the developer may not inhibit any temperature rise due to heat absorption from the outside air, though it is possible to inhibit through heating by the heaters a temperature drop due to outward heat dissipation from the tank D and from the developer. Therefore, the conventional arrangement involves a critical drawback that if the outside temperature is higher than the preset temperature for developing treatment, temperature control is completely impossible.